This invention relates to activation of olefin polymerization catalysts.
Supported chromium oxide catalysts can be used to prepare olefin polymers in a hydrocarbon solution to give a product having excellent characteristics from many standpoints. Supported chromium oxide catalysts can also be used to prepare olefin polymers in a slurry system wherein the polymer is produced in the form of small particles of solid material suspended in the diluent. This process, frequently referred to as a particle-form process, has the advantage of being less complex but does not produce polymers which are exactly comparable to the solution polymers. There are certain applications where it is necessary to have the properties associated with solution process polymer. It has been found previously that a satisfactory composition can frequently be obtained by blending a solution form polymer and a particle form polymer, but this involves the extra expense of compounding the blend. Specifically, in the area of blow molding of bottles and the like, it is desired to have polymer with a broad molecular weight distribution and low die swell, characteristics not generally associated with particle-form polymer. Consequently, it has been necessary to produce these grades of resins either from solution-form polymer or from blends of solution-form and particle-form polymer.